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AIJCR
10.5005/jp-journals-10013-1282
Anatomicosurgical References for Endoscopic Localization of Sphenopalatine
Foramen: A Cadaveric Study
Original Article
Anatomicosurgical References for Endoscopic
Localization of Sphenopalatine Foramen:
A Cadaveric Study
1
Anjali Aggarwal, 2Tulika Gupta, 3Daisy Sahni, 4Ashok Gupta
ABSTRACT
Source of funding: Nil
Introduction: In patients with posterior epistaxis, generally
the source of bleeding is branches of sphenopalatine artery
(SPA), which enter the nasal cavity through the sphenopalatine
foramen (SPF). Cases of intractable massive bleeding may
require endonasal endoscopic occlusion of these vessels.
Conflict of interest: None
Materials and methods: A total of 32 hemisections of formalinfixed cadaveric heads were used. The anatomic variations of
SPF, its distance from anatomical landmarks, and angle of
elevation of endoscope were studied so as to facilitate accurate
localization of the foramen and endoscopic arterial ligation.
Results: The SPF was generally single; however, multiple
exits in the form of accessory foramina were found in 36.75%
hemisections. The transition of superior and middle meatuses
was the most common location of SPF, followed by the superior
meatus, and middle meatus was the least common site. The
accessory foramina were commonly present in the superior
meatus. Ethmoid crest was distinctly visible in all but two cases.
In majority of the cases, the SPF was located within a range of
55 to 65 mm from the anterior nasal spine (ANS); 60 to 70 mm
from piriform aperture, 50 to 60 mm from limen nasi, 20.1 to
25 mm vertically above the floor of nasal cavity, and 8 to 15 mm
from the inferior turbinate (IT). The angulation of SPF from the
floor of nasal cavity was 20 to 30°.
Conclusion: Exploration of lateral nasal wall (LNW) up to
middle meatus would minimize the risk of missing any arterial
branch, and the data of distance from the anatomical references would assist in more precise localization of SPF during
endoscopic ligation or cauterization of the branches of the SPA.
Keywords: Endoscopy, Posterior epistaxis, Sphenopalatine
artery, Sphenopalatine foramen.
How to cite this article: Aggarwal A, Gupta T, Sahni D, Gupta
A. Anatomicosurgical References for Endoscopic Localization
of Sphenopalatine Foramen: A Cadaveric Study. Clin Rhinol
An Int J 2016;9(3):109-114.
1,2
Assistant Professor, 3Professor and Head, 4Professor
1-3
Department of Anatomy, Postgraduate Institute of Medical
Education and Research, Chandigarh, India
4
Department of Otolaryngology, Head and Neck Surgery
Postgraduate Institute of Medical Education and Research
Chandigarh, India
Corresponding Author: Anjali Aggarwal, Assistant Professor
Department of Anatomy, Postgraduate Institute of Medical
Education and Research, Chandigarh, India, Phone:
+911722755203, e-mail: [email protected]
INTRODUCTION
Epistaxis is one of the commonest clinical presentations
that the otolaryngologists come across. Most cases of
epistaxis, particularly if the source of bleeding is an anteriorly located vessel, are easy to manage. Bleeding from
posteriorly located vessel though less common is difficult
to control.1 Several authors have concluded that the lateral
nasal wall (LNW) is the primary site of refractory posterior epistaxis. Posterior nasal cavity, particularly mucosa
of LNW and septum, is perfused mainly by branches
of sphenopalatine artery (SPA).2 Sphenopalatine artery
enters the nasal cavity through sphenopalatine foramen
(SPF). Cases of intractable massive bleeding refractory
to conservative management require surgical interruption of arterial blood supply of nasal mucosa. Endonasal
endoscopic occlusion of SPA is considered a safer option.3
Though the results of endoscopic SPA ligation are
encouraging, failure in localization and endoscopic ligation of SPA has been encountered in 2 to 20% of cases,
particularly by beginners early in their endoscopic experience.4 Key to successful identification of the bleeding
vessel and further therapeutic intervention is accuracy
in topographic localization of SPF. Surgical approaches
rely on landmarks that can assist in localizing SPF. Efforts
have been made in the past to search reliable location
landmarks. Anterior nasal spine (ANS), horizontal plate
of palatine bone, and bony crista ethmoidalis are few such
examples.1,4,5 Large variations with regard to the measurements of distance of SPF from the landmarks have been
reported in the literature.5 The current study was planned
to provide a detailed account of the variations of the SPF
and to determine the location of SPF by taking measurements from anteriorly and posteriorly located intranasal
landmarks relevant to endoscopic localization of SPA and
the best angle for endoscope elevation to reach the SPF.
MATERIALS AND METHODS
The study was conducted on 32 sagitally sectioned formaldehyde-preserved adult cadaveric head hemisections
Clinical Rhinology: An International Journal, September-December 2016;9(3):109-114
109
Anjali Aggarwal et al
(16 right and 16 left). Corps with history of nasal trauma
or any endonasal surgery were excluded from the study.
Vertical incision was given in the mucosa of LNW and
extending upward from the posterior end of the inferior
turbinate (IT) to the sphenoid sinus. Mucosa flap was
elevated until SPF was indentified. Photodocumentation
of all cases was done.
Anatomical Observations
Lateral nasal walls of hemisections were studied under
magnoscope (magnification of lens 2×) and following
anatomical features were recorded:
• Presence of well-defined ethmoid crest of perpendicular plate of palatine bone.
• Localization of SPF in relation to ethmoid crest.
Sphenopalatine foramen was considered located in the
superior meatus if the lower margin of foramen lies
above the level of ethmoid crest; at the transition of
superior and middle meatus if the crest lies in line
of middle of the foramen; at the middle meatus if
the upper margin of foramen lies below the level of
ethmoid crest.
• Localization of accessory foramen if any.
Anatomical Measurements
• Distances of inferior margin of SPF and accessory
foramen were measured from the following anatomical landmarks (Fig. 1):
– Anterior nasal spine (ANS−SPF)
– Plane of piriform aperture (PA−SPF)
– Limen nasi (LN−SPF)
– Floor of nasal cavity (vertical distance) (NF−SPF)
– Posterior end of IT (IT−SPF)
• Angle of foramen from floor of nasal cavity: For
measuring the angle, a transparency was placed on
the section. Two lines, one extending from the ANS
along the floor of nasal cavity and second from the
ANS to inferior margin of SPF, were drawn on the
transparency. Angle between these two lines was
measured. This angle indicated the angle of elevation
of endoscope introduced through the PA.
For linear and angular measurements, digital caliper
of precision 0.02 mm (Mitutoyo Co., Kawasaki, Japan) and
protractor respectively, were used.
RESULTS
Anatomical Observations
Ethmoid crest of perpendicular plate of palatine bone was
distinctly visible in 30 (93.75%) LNWs. In one hemisection, part of LNW was hypoplastic, represented by cartilaginous tissue, and ethmoid crest was not visible, and
in another specimen, ethmoid crest was not appreciable
(Figs 2A to D). Twenty (62.5%) LNWs presented solitary
opening of SPF. More than one foramen was seen in 12
(37.5%) LNWs, double in 10 (31.25%), and triple in 2 (6.25%).
In cases with multiple foramina, the largest foramen was
considered as the main SPF, and smaller was taken as the
accessory foramen.
Localization of the Foramen
The main SPF was lying above the line of ethmoid crest,
implying position in the superior meatus in 8 (25%) cases;
at the level of ethmoid crest indicating the transition of
superior and middle meatus in 17 cases (53.12%); and in
5 cases (15.62%), SPF was present below the ethmoid crest
indicating position in the middle meatus. Two cases in
which ethmoid crest was not visible, SPF was located
above the line of attachment of middle meatus, suggesting its position in the superior meatus. Thus, in 10 cases
(31.25%), the SPF was positioned in the superior meatus.
In cases with double SPF, the accessory foramen was
situated in the superior meatus in eight (25%) cases and
middle meatus in two (6.25%) cases. In one of the cases
with triple foramina, one accessory foramen was lying
above and the other below the main SPF in the middle
meatus. In the second case of triple SPF, both accessory
foramina were located in the superior meatus.
Distance from Intranasal Landmarks
Fig. 1: Hemisection of head and neck showing measurements. (SPF:
Sphenopalatine foramen; ANS: Anterior nasal spine; PA: Piriform
aperture; LN: Limen nasi; NF: Nasal cavity floor; IT: Inferior turbinate)
110
The distances of SPF from the landmarks are given in
Table 1; they varied widely. We categorized the measurements into groups. For anteriorly located references, the
groups were <50 mm; 50.1 to 55 mm; 55.1 to 60 mm; 60.1
to 65 mm, and >65 mm (Graph 1). From the ANS, the SPF
was lying in the range of 50 to 55 mm in 12.5% cases;
55.1 to 60 mm in 21.9% cases; 60.1 to 65 mm in 50% cases,
AIJCR
Anatomicosurgical References for Endoscopic Localization of Sphenopalatine Foramen: A Cadaveric Study
A
B
C
D
Figs 2A to D: Dissected LNW showing variations of number and position of SPF: (A) SPF lying in the line of ethmoid crest (SPF at the
transition of superior and middle meatus); (B) Double SPF – the main SPF and the accessory foramen lying in the superior meatus;
(C) LNW is hypoplastic, ethmoid crest is not visible, and SPF is located in the superior meatus; and (D) Triple SPF – the main SPF
at the transition of superior and middle meatuses, one accessory in the superior and the other in the middle meatus
Table 1: Summary of the results
Parameters
ANS–SPF (mm)
PA–SPF (mm)
Limen nasi–SPF (mm)
Nasal floor–SPF (mm)
IT–SPF (mm)
Angle of endoscope insertion
Range
50.00–68.42
49.00–70.14
45.00–60.00
18.67–26
8.32–20.00
14.00°–34.00°
Mean ± SD
60.69 ± 4.72
61.90 ± 5.57
54.26 ± 3.23
22.16 ± 2.00
13.14 ± 2.55
24.94°± 3.35
SE
0.83
0.97
0.57
0.51
0.46
0.59
and 65 to 68.42 mm in the remaining 15.6% cases. With
piriform aperture taken as a reference, the SPF was lying
in the range of 50 to 55 mm in 12.5% cases; 55.1 to 60 mm
in 15.6%; 60.1 to 65 mm in 34.4%; 65.1 to 70 mm in 37.5%
cases. From another anteriorly located landmark, the
limen nasi, the measurements were 45 to 50 mm in 3.1%;
50.1 to 55 mm in 62.5%; 55.1 to 60 mm in 31.3%; 60.1 to 65
mm in 3.1% cases. From these observations, we evaluated
the range in which majority cases were falling. In 71.9%
cases, ANS−SPF distance was lying in the range of 55.1
to 65 mm, and PA−SPF distance was lying in the range of
60.1 to 70 mm. In 93.8%, the SPF was lying in the range of
Median
61.00
62.50
54.00
22.6
13
26°
Mode
64.92
67
54.21
23
15
26
95% confidence interval
58.96–62.35
59.86–63.82
52.99–55.32
21.59–23.22
12.15–14.03
23.73°–26.14°
Skewness
–0.407 (SE = 0.414)
–0.685 (SE = 0.414)
–0.131 (SE = 0.414)
–0.730 (SE = 0.414)
–0.112 (SE = 0.414)
–0.793 (SE = 0.414)
50.1 to 60 mm from the limen nasi. (Frequency distribution is shown in the bar diagram in Graph 1.)
Average perpendicular distance of SPF from the floor
of nasal cavity was 22.16 mm ± 2 (18.67 to 26 mm). This
distance was 18.67 to 20 mm in 6 (18.75%) cases; 20.1 to
25 mm in 24 (75%) cases; and 25.1 to 26 mm in 2 (6.25%)
cases (Graph 2). From the posterior end of IT, the distance
range was 8.32 to 10 mm in 18.75% cases; 10.1 to 15 mm in
21 (65.25%) cases; 15.1 to 20 mm in 15.62% cases. (Distribution of data shown in scatter plot in Graph 3.)
The angle between the floor of nasal cavity and the
line joining ANS and SPF varied from 14 to 34°. The
Clinical Rhinology: An International Journal, September-December 2016;9(3):109-114
111
Anjali Aggarwal et al
Graph 1: Frequency of five groups of each parameter (SPF–
ANS; SPF–PA; SPF–LN)
Graph 2: Frequency of angle of elevation of endoscope from
the floor of nasal cavity
observed in the mean values of two measurements. Most
of the values were between ±1.96 standard deviation (SD).
DISCUSSION
Graph 3: Scatter plot showing distribution of data of distance of
SPF from floor of nasal cavity and inferior turbinate
angle was <20° in 3.1%, 20.1° to 25° in 31.3%, 25.1° to 30°
in 62.5% cases, 30.1° to 34° in 3.1% cases. In majority of
the cases (93.8%), the angle was lying between 20.° and
30° (Graph 2).
Statistical Analysis
A test (p > 0.05) and visual inspection of histogram
and Q–Q plot showed that the distances of ANS, PA,
IT, and nasal floor were approximately normally distributed with a skewness of 0.407 [standard error (SE)
= 0.414], 0.685 (SE = 0.414),. 112 (SE = 0.414), and 0.730
(SE = 0.414) respectively, whereas the distance of limen
nasi (p < 0.05) from SPF was significantly skewed with
a skewness of –0.131 (SE = 0.414). Similarly, the angle
was also found to be significantly skewed (p < 0.01)
with a skewness of –0.793 (SE = 0.414).
Bland–Altman plots showed that measurements
obtained from piriform aperture and ANS were interchangeable as no significant (p > 0.05) differences were
112
Nasal mucosa receives blood supply mainly from ophthalmic branch of internal carotid artery and maxillary
branch of external carotid artery. In pterygopalatine fossa,
the maxillary artery gives off SPA, which passes through
SPF, the only communication between the fossa and nasal
cavity. In order to reach the SPA, it is ideal to know the
variations and location of the SPF.
Bolger et al1 in 1999 described a landmark in LNW,
which leads to SPF, the crista ethmoidale of perpendicular
plate of palatine bone to which the middle turbinate joins.
Wareing and Padgham6 proposed a classification of localization of SPF utilizing its relation with the ethmoid crest.
Pádua and Voegels4 supported the recommendations
of Bolger et al1 by finding it in 100% of the specimens.
This classification was followed by many researchers to
describe the location of SPF. According to Budrovich and
Seatti,7 this could be well recognizable in hemisection of
head; however, for endoscopically locating the SPF, the
ethmoid crest is not well marked enough in every skull
and not easy to locate. In two of our specimens, ethmoid
crest was not discernible at all. In one case, part of LNW
was hypoplastic (represented by sheet of cartilaginous
tissue), accounting for the absence of ethmoid crest. We
reviewed the literature and did not come across any such
case. Though the percentage of the absence of ethmoid
crest is small, this fact cannot be ignored and thus reliability of this reference in every case is questionable.
With regard to number of SPF varying from one to
three, our results were in accordance with published literature.8,9 Presence of single foramen was the commonest
observation. The incidence of multiple foramina recorded
in our specimens (36.75%) was close to 38.5% recorded by
AIJCR
Anatomicosurgical References for Endoscopic Localization of Sphenopalatine Foramen: A Cadaveric Study
Nikolic.8 Scanavini et al9 found multiple foramina in 13%
of the cases. Double foramina have been seen in 10 to 12%
of the cases. 6,8-10 Percentage of double foramina recorded
in our study (31.5%) was close to the one presented by
Nikolic.8 Occurrence of triple foramina is relatively less
common. Nikolic8 detected triple orifice in 39 cases (5.5%)
of large samples studied, and Scanavini et al9 found in only
one of the specimens (1.9%). Despite the small sample size
of our study, we found triple orifice in two cases (6.25%).
Positional variability of the SPF is not unusual. The SPF
has been found in LNW in any position from recess above
superior turbinate to middle meatus. 4,6,9,11,12 We observed
the main SPF most frequently at the transition of superior
and middle meatuses (53.12%). The foramen was at the
level of superior meatus in 31.25% and middle meatus in
15.62% specimens. Our data were quite close to the one
given by Wareing and Padgham6 collected from bone
specimens (56% at the transition; 35% in superior meatus;
9% in middle meatus). This is further supported by work
done by Pádua and Voegels4 who found the foramen at
the transition in majority of specimens examined (86.9%)
and in the remaining 13.1% cases in the superior meatus.
Midilli et al12 found at the transition in 80% and in the
superior meatus in 20% LNW. Contrary to these observations, some other studies found SPF most frequently in
the superior meatus. Lee et al11 noted at this site in 90%
specimens and Scanavini et al9 in 81.5%. Sphenopalatine
foramen has also been spotted in the middle meatus,
with recorded incidence of 1.9 to 9%.6,9,10 We found SPF
in relatively higher number (15.6%). Fourth though least
common position is superior to the attachment of superior
turbinate by Lee et al11 in 10% specimens.
The accessory foramina are generally found anterior
to the main SPF. Most of the researchers have found them
in the middle meatus. In our samples, they were detected
most commonly in the superior meatus and in a few cases
at the transition of superior and middle meatuses. Thus,
in view of getting best results and exposing all potential
accessory foramina, we recommend the exploration
extending from superior turbinate to the attachment of
superior turbinate to middle meatus.
This variation in the number and position of SPF may
be due to variation in the entry of SPA into the nasal
cavity. Lee et al11 found two to four branches arising from
SPA in pterygopalatine fossa, and each branch entered
independently into the nasal cavity. This number corresponds to variation of arterial branches exiting through
accessory foramina resulting in multiple foramina. This
alteration in the input of the arterial nasal irrigation is relevant while managing severe epistaxis through ligation
of SPA. Numerical variation is considered to be the major
factor for failure of complete ligation of SPA branches.
Schwartzbauer et al2 in 8 out of 19 dissections (42%) found
SPA emerging into the nasal cavity through the accessory
foramen situated posterior to SPF and recommended that
dissection should be continued posterior.
The second part of our study consisted of measurement of SPF from anatomical landmarks to get closest
estimate of SPF from the references. The most certain
way of reaching SPF is to know its exact location, and
therefore, establishment of a constant reference point is
of great importance for successful endoscopic ligation
or cauterization of SPA. In the past, attempts have been
made to identify satisfactory references for locating the
foramen. The ANS is one of the most commonly used references. Reviewing the literature reveals that the foramen
lies between 51 and 81 mm from the ANS, and the average
distance varies from 59 to 66 mm.4,9,13 The values are
based on dry skull or cadaveric dissection. Our results
(average 60.69 ± 4.72, range 50 to 68.42) closely matched
with those of Scanavini et al9 and Hadoura et al.13 Data
in the literature as well as our study show wide range of
these measurements. Therefore, we evaluated the range
of majority of the cases. In majority of the cases (72%), the
infraorbital foramen was situated in the narrow range of
55.1to 65 mm distance from ANS (Table 2).
Table 2: Comparison with the published literature
Scanavini et al9
(n = 12 cadavers)
Hadoura et al13
n = 28
Prades et al5
(n = 12 skulls)
Lee et al11 (n = 50
hemisections)
Pádua and Voegels 4
(n = 122 cadavers)
Current (2015) (n = 32
hemisections)
ANS–SPF
(mm)
58.98 ± 4.36
(51.50-68.35)
59 ± 3.978
(50–69)
–
Limen nasi–
SPF (mm)
–
Nasal floor–SPF
(mm)
–
IT–SPF (mm)
–
48.48 ± 3.51
(40.5–57.5)
–
–
–
–
–
18.27 (15.09–20.87)
13(9–14.85)
Angle from floor
of nasal cavity
26.20°± 5.64°
(20°–32°)
22.56°± 3.214°
(14°–32°)
–
–
59.4 ± 4.2
49.1 ± 3.7
–
–
–
66 ± 5.350–81
–
–
–
–
–
60.70 ± 4.80
(50–68.42)
61.90 ± 5.57
(48.6–70.14)
54.26 ± 3.17
(45–60)
22.37 ± 2.28
(18.67–26)
13.14 ± 2.55
(8.32–20)
24.94° ± 3.35°
(14°–36°)
PA–SPF (mm)
–
Clinical Rhinology: An International Journal, September-December 2016;9(3):109-114
113
Anjali Aggarwal et al
Plane of PA is another landmark, which may guide
surgeons as to how far they should introduce the endoscope to reach the foramen. Average observed in our
study (61.9 ± 5.57) was close to the value recorded by Lee
et al11 (59.4 ± 4.2 mm). The distance measured by Hadoura
et al13 showed lower value. Our results revealed that in
majority (72%) of the cases, the SPF was located in the
narrow range of 60 to 70 mm.
Limen nasi is another though less studied reference.
Lee et al11 recorded average distance of 49.1 ± 1.97 mm
from it. Our results showed higher value for this distance.
However, in 93.8%, the SPF was lying in the range of 50.1
to 60 mm. Comparative assessment of anterior anatomical
references showed least variation in the distance range
from limen nasi, since in more than 90% of the cases,
the SPF was located 50.1 to 60 mm from limen nasi. Out
of all anteriorly located landmarks, the distance of SPF
from limen nasi showed the least variation. Best reference
appears to be limen nasi.
Prades et al5 found inferior border of SPF situated at an
average 18.27 mm (15.09–20.67 mm) above the horizontal
plate of palatine bone. Our results for same measurement
were on the higher side (22.19 ± 1.97 mm). In 75% of the
midsections studied by us, the SPF was lying within the
range of 20.1 to 25 mm from the floor of the nasal cavity.
Prades et al5 worked on bony skull, whereas we studied
on cadaveric specimens, which is more close to real-life
situations. Another posteriorly situated reference that can
assist in localization of foramen is horizontal lamina of IT.
The mean (13.14 mm) recorded in our study was very close
to the one recorded by Prades et al5 (average 13.04 mm).
In 84% of the cases, SPF was located in the range of 18.32
to 25 mm from IT.
To minimize the number of attempts and enhance the
chances of achieving correct localization of SPF, besides
knowing the relationship to surrounding landmarks,
it is essential to have an idea of the optimum angle of
endoscope elevation. The average recorded in previous
work varied between 22 and 26° and range between
14 and 32°.9,13 Our results were falling in this range. In
93.8% of the cases, the SPF was lying at an angulation
between 20 and 30°.
CONCLUSION
The present study has provided detailed information concerning the variations and localization of SPF. Highlight
of our study is comparative assessment of anatomical
references and provision of distance range with high
likelihood of reaching SPF. This aspect has not been
addressed before. These distance references for the use
114
of the endoscope in endonasal ligation or cauterization
of the branches of the sphenopalatine would assist in
more precise localization and minimizing the risk of
missing any arterial branch. More work needs to be done
particularly in the patients to validate our observations.
To expose all potential accessory foramina, it is advisable
to explore both superior and middle meatuses before
finishing the surgery.
ACKNOWLEDGMENT
The authors wish to thank all who have donated their
body to the Department of Anatomy, Mr Pradeep Sing for
photography, and Mrs Shallu Jagii for statistical analysis.
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